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1、SoftwareEngineeringEvolution&NanagementEffortEstimationCOCOMO-AnEmpiricalEstimationModelforEffortIntroduction:Thestructureofempiricalestimationmodelsisaformula,derivedfromdatacollectedfrompastsoftwareprojects,thatusessoftwaresizetoestimateeffort.Size,itself,isanes
2、timate,describedaseitherlinesofcode(LOC)orfunctionpoints(FP).Noestimationmodelisappropriateforalldevelopmentenvironments,developmentprocesses,orapplicationtypes.Modelsmustbecustomised(valuesintheformulamustbealtered)sothatresultsfromthemodelagreewiththedatafromthe
3、particularenvironment.Thetypicalformulaofestimationmodelsis:E=a+b(S)cwhere;Erepresentseffort,inpersonmonths,Sisthesizeofthesoftwaredevelopment,inLOCorFP,and,a,b,andcarevaluesderivedfromdata.Therelationshipseenbetweendevelopmenteffortandsoftwaresizeisgenerally:ESTh
4、isgraphdemonstratesthattheamountofeffortacceleratesassizeincreases,i.e.,thevaluecinthetypicalformulaaboveisgreaterthan1.COCOMO:WhenBarryBoehmwrote'SoftwareEngineeringEconomics',publishedin1981,heintroducedanempiricaleffortestimationmodel(COCOMO-COnstructiveCOstMOd
5、el)thatisstillreferencedbythesoftwareengineeringcommunity.Themodelhasbeenreviewedsince1981anddetailsoftherevisedandupdatedCOCOMO2model,canbeobtainedat:http://sunset.usc.edu/research/index.html.TheoriginalCOCOMOmodelwasasetofmodels;3developmentmodes(organic,semi-de
6、tached,andembedded)and3levels(basic,intermediate,andadvanced).COCOMOmodellevels:Basic-predictedsoftwaresize(linesofcode)wasusedtoestimatedevelopmenteffort.Intermediate-predictedsoftwaresize(linesofcode),plusasetof15subjectivelyassessed'costdrivers'wasusedtoestimat
7、edevelopmenteffort.page:4of4SoftwareEngineeringEvolution&NanagementEffortEstimationAdvanced-ontopoftheintermediatemodel,theadvancedmodelallowsphase-basedcostdriveradjustmentsandsomeadjustmentsatthemodule,component,andsystemlevel.COCOMOdevelopmentmodes:Organic-smal
8、lrelativelysmall,simplesoftwareprojectsinwhichsmallteamswithgoodapplicationexperienceworktoasetofflexiblerequirements.Embedded-thesoftwareprojecthastigh
